It is known that (7S,9S)-9-acetyl-9-amino-7-[(2-deoxy-β-D-erythro-pentopyranosyl)oxy]-7,8,9,10-tetrahydro-6,11-dihydroxy-5,12-naphthacenedione which has the following Formula (1):
(hereinafter, referred to as amrubicin) and a salt thereof are useful as a cancer chemotherapeutic agent (see, Patent Reference 1). It is also known that there are several crystal forms of amrubicin hydrochloride, and one of them has a high thermostability (see, Patent Reference 2).
Anthracycline compounds such as amrubicin are unstable in a solution. When formulating such compounds as an injection, generally, they are put into a vial as a powder or lyophilized to prepare an injection formulation wherein the compound is to be dissolved before use.
Furthermore, as a stabilized formulation of amrubicin, the formulation comprising L-cysteine or a salt thereof is known (see, Patent Reference 3 and Patent Reference 4).
[Patent Reference 1] JP 1992(3)-5397 A                (Corresponding U.S. Pat. No. 4,673,668 B)        
[Patent Reference 2] JP 2975018 B                (Corresponding U.S. Pat. No. 6,376,469 B)        
[Patent Reference 3] JP 2603480 B                (Corresponding U.S. Pat. No. 4,952,566 B)        
[Patent Reference 4] WO 2004/050098                (Corresponding US patent application: US 2006/0003949 A)        